ORIGINAL ARTICLE

Congenital hypothyroidism: no adverse effects of high dose thyroxine treatment on adult memory, attention, and behaviour

B Oerbeck¹, K Sundet², B F Kase³, S Heyerdahl¹

¹ Centre for Child and Adolescent Mental Health, Eastern and Southern Norway
² Department of Psychology, University of Oslo, Norway
³ Department of Pediatric Research, Rikshospitalet University Hospital, Oslo, Norway

Correspondence to:
Correspondence to:
Dr B Oerbeck
Regional Centre for Child and Adolescent Mental Health, PO box 23 Taasen, N-0801 Oslo, Norway; beate.orbeck{at}r-bup.no

Background: In congenital hypothyroidism (CH) it has been questioned whether high dose thyroxine replacement therapy has detrimental effects on memory, attention, and behaviour.

Aims: To describe memory, attention, and behaviour problems in young adults with CH, and to study possible negative effects of high dose thyroxine replacement therapy.

Methods: A cohort based follow up study of 49 young adults (mean age 20 years) with early treated CH, and sibling controls (n = 41).

Results: Controlled for age and sex, the CH group attained significantly lower scores than sibling controls on some tests of memory (Wechsler Logical Memory part II: 12.9 versus 17.8; difference 5.2, 95% CI 3.6 to 6.8) and attention (Wechsler Freedom From Distractibility factor: 95.6 versus 104.8; difference 9.9, 95% CI 6.4 to 13.4). They rated themselves with more behaviour problems than did sibling controls (52.7 versus 44.7; difference –7.6, 95% CI –11.2 to –4.0) on the Achenbach Self Report. A high thyroxine starting dose, high serum thyroxine treatment levels during the first six childhood years, and high levels at assessment had no adverse effects on outcome measures at age 20. On the contrary, the results suggest better outcome with higher childhood treatment levels.

Conclusions: Long term outcome revealed deficits in some aspects of memory, attention, and behaviour in young adults with CH relative to sibling controls. No adverse effects of high dose thyroxine therapy were found on measures of memory, attention, and behaviour problems.

Abbreviations: CAVLT, Children’s Auditory Verbal Learning Test; CH, congenital hypothyroidism; CVMT, Continuous Visual Memory Test; DVT, Digit Vigilance Test; FFD, Wechsler Revised Freedom from Distractibility factor; RCFT, Rey Osterrieth Complex Figure; SES, socioeconomic status; T4, thyroxine; TMT, Trail Making Test; TSH, thyroid stimulating hormone; WCST, Wisconsin Card Sorting Test; WMS-R-LM, Wechsler Logical Memory Test, Story A

Keywords: congenital hypothyroidism; adult outcome; thyroxine

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congenital hypothyroidism: no adverse effects of high dose thyroxine treatment on adult memory...

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ADC Online, 4 Feb 2005 [Full text]